Preparing surfaces for etching and in etching such surfaces.



Harman dramas Parana FRANCIS H. THIBODO AND SEBASTIAN S. PECKINPAUGH, OF GREENBAY, l/VISCONSIN; SAID PEOKINPAUGH ASSIGNOR TO RUTHERFORD B. H. MACRORIE, OF GREENBAY, WISCONSIN.

PREPARING SURFACES FOR ETCHING AND IN ETCHING'SUCH SURFACES.

SPECIFICATION forming part of Letters Patent No. 706,280, dated August 5, 1902.

Application filed June 12,1899. Serial No. 720,248. (No specimens.)

To all whom it may c n rnexposed to the light. If the plate to be etched 50 Be it known that we, FRANCIS H. THIBODO coated with the above solution is a material and SEBASTIAN S. PECKINPAUGH, citizens of subject to actinic rays, as glass, this expothe United States of America, residing at sure to the light should be made so that the Greenbay, county of Brown, and State of actinic rays reach the coating through the \Visconsin, have invented certain new and glass, which will cause the coating to adhere 55 useful Improvements in Preparing Surfaces more closely to the plate. It the plate used for Etching and in Etching Such Surfaces; as above stated be steel, copper, zinc, or other and we do hereby declare the following to be a opaque substance, the light is allowed to full, clear, and exact description of the instrike directly on the coating specified above.

vention, which will enable others skilled in This exposure to the light is made to render 60 the art to which it appcrtains to apply the thesaid coatinginsoluble. Prepared carbon same. tissue, which is known as carbon tissue,

Heretofore the methods applied by the carbon-paper, or autotype-paper, being I 5 agency of photography for producing photoa patented article of paper coated with gelaetching on glass plates have only been partin and containing any shade of pigment, 65 tially successful, the general character of the after being sensitized in the usual manner work being such that all the lights and shadfor such paper is exposed under negative for ows were not brought out in detail. a time sufficient to make a strong print and The object of our invention is to provide a is then placed upon the surface to be etched,

process of etching which shall be simple and which is that side of the plate of glass, steel, 70 easily carried out and which shall be cheap copper, or zinc which has been coated with and by which large and small surfaces of the solution above mentioned, and this carglass, steel, copper, zinc, and almost any hard bon tissue after being so placed should be material of smooth surface may be successpressed down firmly, so as to adhere to the fully and satisfactorily etched with an exact coating, and is then developed by placing the 75 reproduction of a photographic negative with plate in a developing-pan holding a bath of all the gradations of light and shadow. hot water. After developing the thick back- It will be seen by this specification that ing of the carbon tissue being loosened is rethe time of etching by this process is of shorter moved by taking hold of a corner and pulling duration than all former processes, which is said backing from the plate. This will leave 80 in itself a great benefit and improvement. the developed carbon tissue adhering to the It will be seen from this specification that coating of albumen, water, ammonia, chromeour method of preparing and etching is an alum,and bichromate of ammonia heretofore improvementin many ways from formermethmentioned. The carbon tissue so adhering is ods of preparation and etching and that by then dried by heat or evaporation. The plate 8 5 the use of the herein-described method it is is now ready for etching after being warmednot applicable for etching designs, &c., as in Hydrofluoric gas is generated in a deep metal former methods of etching on glass, the. dish or box, preferably one with an opening To carry out our invention, the material to at the top of such size that the plate to be be etched-glass or such other material suitetched will just cover this opening. The able, steel, copper, or zinc, &c.-is coated plate to be etched is then placed with the with a solution of albumen, one ounce; water, prepared side down, thus allowing the hydrothree ounces; ammonia, ten drops; chromefiuoric gas to attack only the surface so prealum, three drops of a solution consisting of pared. The coating which has been placed chrome-alum ten grains and water one ounce; upon this prepared plate has by its exposure bichromate of ammonia, twenty grains. Afto the light, as specified hereinbefore, beter receiving the above coat the plate is then come insoluble, and the carbon tissue havdried in subdued light and is then taken and ing been developed upon said coating is of such texture as to allow the hydrofluoric gas to penetrate, (only where the light has not acted on the carbon tissue when exposed under the negative,) thus allowing the hydrofluoric gas to cut the plate and from the nature of the coating first mentioned and the carbon tissue causes the plate to assume where the hydrofluoric gas acts upon it an etched appearance. It the plate be glass, it will assume an etched and whitish or frosted or ground -glass appearance. When sufficiently etched, remove and wash with water, thus completing the process. When the plate to be etched is other than glass, the prepared surface is flowed with any acid which will attack and etch it.

The object of the coating of albumen, water, ammonia, chrome-alum, and bichromate of ammonia is to form a medium for holding the carbon tissue on the surface to be etched when placed so that the hydrofluoric gas will act on same, and without said coating the carbon tissue would not adhere to the surface to' be etched, but would peel oif. Also the coating above mentioned is of such consistency that when used in the manner above specified on a glass plate will when the plate is exposed to hydrofluoric gas cause it to assumo an etched or frosted or ground-glass appearance.

Having thus described ourinvention, What we claim as new therein, and desire to secure by Letters Patent, is

1. In the art of etching glass, or similar subjecting the sheet of glass to the action of hydrofluoric gas, eroding the surface of the glass; and in then removing the remaining portion of the coating.

2. In the art of etching glass, or similar substances, the process which consists in covering one surface of a sheet of glass with a coating composedof albumen, water, ammonia, chrome-alum and bichromate of ammonia in the proportions specified; in then drying this coating in subdued light; in then exposing this, coating to the light; in then developing sensitized and exposed carbon tissue on this coating; in then eroding the surface of the plate on which the coating is placed to a depth varying with the protection afforded by the coating; and in then removing the remaining portion of the coating.

FRANCIS H. THIBODO.

SEBASTIAN S. PEOKINPAUGII.

In presence of- C. W. LOMAS, R. B. H. MACRORIE. 

